Method and apparatus for capturing skin print images

Abstract

A system for generating data characteristic of a rolled skinprint in real time. A body part such as a finger contacts a receiving surface of an optical device. The receiving surface is imaged and recorded on an image recording medium during the period of contact. The resulting record is then used to generate digital data representative of the image of the skinprint. This is especially useful for recording a rolled fingerprint image taken on a flat receiving surface.

What is claimed is: 
     
       1. An identification image recording apparatus, comprising: prism means for propagating light corresponding to raised surfaces of a portion of a human body in contact with the prism means, wherein the prism means comprises a light source and a prism, the prism having a receiving surface and a light propagating surface, wherein the receiving surface has reflective properties which change as a function of contact with the human body portion and wherein the light propagating surface propagates light reflected from the receiving surface, the prism and the light source being configured so that propagated light corresponding to areas of the receiving surface in contact with the raised surfaces is higher in intensity than propagated light corresponding to other areas of the receiving surface;   image recording means positioned to continuously receive the propagated light, wherein the image recording means comprises an image recording medium for accumulating the light over a period of time corresponding to a complete finger roll to form a skin print image;   conversion means for converting said skin print image into electrical signals; and   image processing means connected to said image recording means for receiving said electrical signals.   
     
     
       2. The apparatus according to claim 1 wherein the image recording medium comprises a CCD array positioned to continuously receive said propagated light. 
     
     
       3. The apparatus according to claim 2 wherein the conversion means includes means for reading the CCD array. 
     
     
       4. The apparatus according to claim 1 wherein the conversion means includes means for storing the skin print image in memory. 
     
     
       5. The apparatus according to claim 1 wherein the image recording medium comprises an electrophotographic recording system. 
     
     
       6. The apparatus according to claim 1 wherein said prism means further comprises monochromatic filters positioned between the image recording means and the propagating surface of the prism. 
     
     
       7. A method of generating data characteristic of a rolled fingerprint image, wherein the method comprises the steps of: providing an optical device having a finger receiving surface which reflects light as a function of a ridge and valley pattern of a finger brought in contact with the finger receiving surface, a light propagating surface which propagates light reflected from the finger receiving surface and a source of illumination positioned to project light onto the receiving surface;   providing an image recording medium positioned to receive the propagated light;   placing a finger on the finger receiving surface of the optical device;   rolling the finger across the finger receiving surface, wherein the step of rolling occurs over a period of time;   continuously recording the rolled fingerprint image as the finger contacts the finger receiving surface, wherein the step of recording comprises accumulating on said image recording medium, during the period of time the finger is being rolled across the receiving surface, a fingerprint image which varies as a function of intensity of the propagated light over the period of time;   converting the fingerprint image into digital signals; and   generating an array of digital data characteristic of a complete rolled fingerprint image from the digital signals.   
     
     
       8. The method according to claim 7 wherein the step of generating the array includes generating the array in real time as the finger is being rolled. 
     
     
       9. The method according to claim 8 wherein the step of converting the fingerprint image includes determining a threshold value for the digital data to determine presence or absence of contact of the finger with the receiving surface. 
     
     
       10. The method according to claim 7 further including the steps of: detecting that the finger is on the finger receiving surface; and   terminating the step of accumulating if the finger is not in contact with the finger receiving surface.   
     
     
       11. The method according to claim 10 further including the step of activating an alarm if the finger is not detected within a preselected amount of time from the start of image recording. 
     
     
       12. A method of capturing a skin print image, wherein the method comprises the steps of: providing an optical device having a receiving surface which reflects light as a function of a ridge and valley pattern in skin brought in contact with the receiving surface, a light propagating surface which propagates light reflected from the receiving surface and a source of illumination positioned to project light onto the receiving surface;   providing an image recording medium positioned to receive the propagated light;   placing a portion of a human body in contact with the receiving surface;   reflecting light projected from the illumination source off the receiving surface;   propagating the reflected light through the propagating surface;   accumulating a first image as a function of intensity of the propagated light over a first period of time;   accumulating a second image as a function of intensity of the propagated light over a second, nonoverlapping, period of time; and   combining the first and second images to form the skin print image.   
     
     
       13. The method according to claim 12 wherein the step of combining comprises the steps of: digitizing the first and second images to form first and second arrays of pixels, respectively, wherein each pixel has an intensity value;   adding the pixel intensity values of the first and second pixels arrays to produce a third pixel array; and   storing the third pixel array as the skin print image.   
     
     
       14. A method of generating data characteristic of a rolled fingerprint image, wherein the method comprises the steps of: providing an optical device having a finger receiving surface which reflects light as a function of a ridge and valley pattern of a finger brought in contact with the finger receiving surface, a light propagating surface which propagates light reflected from the finger receiving surface and a source of illumination positioned to project light onto the receiving surface;   providing an image recording medium positioned to receive the propagated light;   placing a finger on the finger receiving surface of the optical device;   rolling the finger across the finger receiving surface, wherein the step of rolling occurs over a period of time;   continuously recording the rolled fingerprint image as the finger contacts the finger receiving surface, wherein the step of recording comprises accumulating on said image recording medium, during the period of time the finger is being rolled across the receiving surface, a rolled fingerprint image which varies as a function of intensity of the propagated light over the period of time.   
     
     
       15. The method according to claim 14 wherein the step of recording further comprises the steps of: converting the fingerprint image into digital signals; and   generating an array of digital data characteristic of the rolled fingerprint image from the digital signals.